Gasket

ABSTRACT

A gasket formed by laminating two or more metal plates includes a seal target hole, an annular seal portion sealing an outer peripheral edge of the seal target hole, and a plurality of bolt holes disposed at the outer peripheral side of the seal portion. Each metal plate constituting a thermal deformation coping portion is provided with slits intersecting in a longitudinal direction of the metal plate and each slit constitutes a lamination portion of the metal plate so as not to penetrate in a lamination direction. When one seal target hole is provided, a portion suspended in the seal target hole is formed at the thermal deformation coping portion, and when multiple seal target holes are provided, at least one of portions interposed between the adjacent seal portions and a portion interposed between the adjacent bolt holes is formed at the thermal deformation coping portion.

BACKGROUND Technical Field

The present invention relates to a gasket, and more particularly, to agasket which prevents damage due to thermal expansion or thermalcontraction.

Related Art

As a gasket which prevents deformation or damage due to thermalexpansion or thermal contraction, there is proposed a gasket in which atleast a part of a region of a fluid space adjacent to at least one metalplate among metal plates constituting a lamination gasket is removed(see JP 2001-289325A). In the gasket, apart of the metal plate in aregion in which thermal expansion or thermal contraction easily occursis removed to decrease the number of the laminated metal plates in thisregion, thereby preventing deformation or damage due to the thermalexpansion or thermal contraction of the gasket.

SUMMARY

Incidentally, damage due to the thermal expansion or thermal contractionof the gasket becomes a factor causing a temperature difference in ausage environment and the thermal expansion or thermal contractionoccurs in all metal plates constituting the gasket. Therefore, in thegasket, since there is no measure for the metal plate which is notremoved in the region in which a part of the metal plates is removed,there is concern that the metal plate which is not removed may bedamaged due to the thermal expansion or thermal contraction. The presentinvention has been made in view of the above-described circumstances andan object of the present invention is to provide a gasket capable ofefficiently preventing damage due to thermal expansion or thermalcontraction.

A gasket of the present invention for achieving the above-describedobject is formed by laminating two or more metal plates and includes atleast one seal target hole penetrating in a lamination direction, anannular seal portion sealing an outer peripheral edge of the seal targethole, and a plurality of bolt holes disposed at the outer peripheralside of the seal portion so that fastening bolts are insertedtherethrough, wherein as a thermal deformation coping portion, all metalplates constituting the thermal deformation coping portion are providedwith slits intersecting in a longitudinal direction of the metal plateand these slits constitute a lamination portion of the metal plates soas not to penetrate in the lamination direction, and a portion suspendedin the seal target hole is formed at the thermal deformation copingportion when one seal target hole is provided, and at least one ofportions interposed between the adjacent seal portions and a portioninterposed between the adjacent bolt holes is formed at the thermaldeformation coping portion when a plurality of seal target holes isprovided.

According to the present invention, since a portion in which a change inexpansion or contraction of the metal plate due to the thermal expansionor thermal contraction is relatively large is set as the thermaldeformation coping portion and all metal plates constituting the thermaldeformation coping portion are provided with the slits intersecting thelongitudinal direction thereof, it is possible to absorb the expansionand contraction of the metal plate due to the thermal expansion orthermal contraction by the slits. Accordingly, since it is advantageousto decrease a compressive force generated by the thermal expansion or atensile force generated by the thermal contraction, it is possible toeffectively prevent damage of the gasket due to a change in temperature.Further, in addition to the above-described effect, according to thepresent invention, since the slits of the laminated metal plates areseparated from each other in the longitudinal direction of the thermaldeformation coping portion and the slits are formed so as not topenetrate in the lamination direction, it is possible to prevent anunnecessary penetration portion from being formed at the thermaldeformation coping portion. Accordingly, it is advantageous to prevent adeterioration in sealing performance in the lamination direction of thethermal deformation coping portion generated when the slits areprovided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a first embodiment of a gasketof the present invention;

FIG. 2 is a plan view illustrating the gasket of FIG. 1;

FIG. 3 is a cross-sectional view as viewed from an arrow X1-X1 of FIG.2;

FIG. 4 is a cross-sectional view as viewed from an arrow X2-X2 of FIG.2;

FIG. 5 is a plan view illustrating a second embodiment of the gasket ofthe present invention;

FIG. 6 is a cross-sectional view as viewed from an arrow X3-X3 of FIG.5;

FIG. 7 is a plan view illustrating a third embodiment of the gasket ofthe present invention; and

FIG. 8 is a cross-sectional view as viewed from an arrow X4-X4 of FIG.7.

DETAILED DESCRIPTION

Hereinafter, a gasket according to an embodiment of the presentinvention will be described with reference to the drawings. In FIGS. 1to 8, dimensions are changed in order to easily understandconfigurations and a size of a seal target hole or a bolt hole or adimension such as a thickness and a shape of a metal plate constitutinga gasket are not necessarily to scale with actually manufacturedproducts.

A gasket 1 of a first embodiment according to the present inventionillustrated in FIGS. 1 to 4 is used while being interposed between apipe body 20 and a pipe body 21 having different number of ventilationholes 22. More specifically, the gasket 1 is used for a connectionportion of an exhaust system or a connection portion between an exhaustmanifold and a turbocharger and seals an exhaust gas passing through thepipe bodies 20 and 21 while being interposed between the pipe body 20and the pipe body 21.

As illustrated in FIG. 1, in a joint structure for connecting the pipebodies 20 and 21 having different number of ventilation holes 22, astructure is obtained in which a partition portion 23 is provided in thepipe body 21 having a relatively large number of ventilation holes 22 todivide the ventilation holes 22 of the pipe body 20 having a relativelysmall number of ventilation holes 22. In the embodiment, the gasket 1which is used while being interposed between the pipe body 20 having oneventilation hole 22 and the pipe body 21 having two ventilation holes 22is exemplified. Each of the pipe body 20 and the pipe body 21 includesthe same rectangular flange portion and each flange portion is providedwith four bolt holes 24 through which fastening bolts are inserted.

The gasket 1 is formed by laminating four metal plates 6. As the metalplate 6, for example, a mild steel plate, a stainless steel annealedmaterial (annealed material), a stainless steel tempering material(spring steel plate), or the like is used. The gasket 1 includes anouter peripheral portion 2 which is in contact with both end surfaces ofthe pipe body 20 and the pipe body 21 while being interposed between twopipe bodies 20 and 21 and a partition protector 3 which coats only theend surface of the partition portion 23 of the pipe body 21 while notcontacting the end surface of the pipe body 20.

As illustrated in FIG. 2, the outer shape of the outer peripheralportion 2 is formed in a rectangular shape which is the same as theouter shapes of the flange portions of the pipe bodies 20 and 21. Theouter peripheral portion 2 includes one seal target hole 7 whichpenetrates the metal plate 6 in the lamination direction, an annularseal portion 8 which seals the outer peripheral edge of the seal targethole 7, and four bolt holes 9 which are disposed at the outer peripheralside of the seal portion 8 and through which fastening bolts areinserted.

The seal target hole 7 is formed in a square shape corresponding to theventilation hole 22 of the pipe body 20 and the belt-shaped partitionprotector 3 is provided to be suspended in the center of the seal targethole 7. As the seal portion 8, a structure in which a bead is formed byprotruding or depressing the metal plate 6 in the lamination direction,a structure in which a shim is provided by a separate metal plate, astructure in which an end portion of the metal plate 6 is covered by afold-back portion obtained by folding back an end portion of the othermetal plate 6, and a structure in which a grommet is fitted can beexemplified.

When the pipe body 20 and the pipe body 21 are directly connected toeach other, the end surface of the partition portion 23 is exposed whilenot contacting the pipe body 20. For this reason, a high-temperaturefluid such as an exhaust gas passing through the pipe body 20 directlyhits the end surface of the partition portion 23 of the pipe body 21.For that reason, when the pipe body 21 is formed of a metal such asaluminum having a low melting point, there is a concern that thetemperature of the end surface of the partition portion 23 rises and theend surface is melted. Here, the gasket 1 is used in order to secure thesealing performance at the joint portion having different number ofventilation holes 22 and to prevent the melting of the end surface ofthe partition portion 23.

As illustrated in FIG. 3, when the gasket 1 is used while beinginterposed between the pipe body 20 and the pipe body 21, thehigh-temperature exhaust gas passing through the seal target hole 7 ofthe pipe body 20 directly hits the partition protector 3 which is coatedand protects the end surface of the partition portion 23. Therefore, inthe gasket 1 of the embodiment, since the partition protector 3 becomesa portion in which a change in expansion or contraction of the metalplate 6 due to the thermal expansion or thermal contraction isrelatively large, the partition protector is formed by a thermaldeformation coping portion 10 (a shaded portion in FIGS. 1 to 4) of thepresent invention. The outline arrows of FIGS. 3 and 4 indicate the flowof the exhaust gas.

As illustrated in FIG. 2, in the gasket 1 of the present invention, aslit 11 intersecting the longitudinal direction of the thermaldeformation coping portion 10 is provided in all metal plates 6 formingthe thermal deformation coping portion 10 and these slits 11 constitutea lamination portion of the metal plates 6 so as not to penetrate in thelamination direction. The longitudinal direction of the thermaldeformation coping portion 10 of the gasket 1 is a direction in whichthe partition protector 3 extends to traverse the seal target hole 7.

In the embodiment, each slit 11 of the thermal deformation copingportion 10 is formed to cross the partition protector 3. In theembodiment, the linear slit 11 is formed, but the shape of the slit 11is not particularly limited. In addition, the slit 11 may be formed in,for example, a curved or serrated shape. Each slit 11 is disposed at thecenter portion of the thermal deformation coping portion 10 in thelongitudinal direction and is formed so as not to overlap the slit 11 ofthe adjacent metal plate 6. The center portion of the thermaldeformation coping portion 10 in the longitudinal direction is, forexample, a center region when the length L of the thermal deformationcoping portion 10 in the longitudinal direction is divided into threeparts.

The slit width W of each slit 11 of the thermal deformation copingportion 10 in the longitudinal direction is set, for example, based on alinear expansion coefficient (a thermal expansion coefficient) α of themetal plate 6 constituting the thermal deformation coping portion 10, atemperature difference ΔT of the thermal deformation coping portion 10when the gasket 1 is used, and a length L of the thermal deformationcoping portion 10 in the longitudinal direction. More specifically,since an expansion/contraction change amount of the metal plate 6 due tothermal expansion or thermal contraction is proportional to each of thetemperature difference ΔT and the length L, the slit width W is setbased on the product of the linear expansion coefficient α, thetemperature difference ΔT, and the length L. The temperature differenceΔT is a temperature difference between a high temperature and a lowtemperature of the thermal deformation coping portion 10 assumed at thetime of using the gasket 1, and the length L is, in the embodiment, alength of the partition protector 3 in the longitudinal direction.Accordingly, both slits 11 of the metal plates 6 constituting thethermal deformation coping portion 10 are set not to contact each otherat the time of using the gasket 1.

In the embodiment, all slits 11 formed in the metal plates 6 ofrespective layers are set to have the same slit width W, but when thelinear expansion coefficient α of the metal plate 6 constituting eachlayer, the temperature difference ΔT in a usage state, or the length Lof the thermal deformation portion 10 in the longitudinal direction isdifferent, all slits 11 forming in the metal plates 6 of respectivelayers may be set to have different slit widths W.

As illustrated in FIG. 4, in the embodiment, the slits 11 of the metalplates 6 which are adjacent to each other in the lamination directionare respectively disposed at positions separated from each other in thelongitudinal direction of the thermal deformation coping portion 10. Adistance between the slits 11 adjacent to each other in the laminationdirection is set so that the slits 11 adjacent to each other in thelamination direction at the time of using the gasket 1 do not overlapeach other. Further, the slits 11 are disposed so that the slits 11adjacent to each other in the lamination direction are respectivelylocated at different sides with the center position C of the thermaldeformation coping portion 10 in the longitudinal direction as aboundary. In other words, the slits 11 which are adjacent to each otherin the lamination direction are disposed to be staggered with the centerposition C as a boundary.

The slit 11 can be formed by, for example, a press die which is commonto a press die for forming the seal target hole 7 or the bolt hole 9 inthe metal plate 6. Then, the gasket 1 can be manufactured by laminatingthe metal plates 6 respectively forming the slits 11.

As described above, in the gasket 1 of the present invention, a portionin which a change in expansion or contraction of the metal plate 6 dueto the thermal expansion or thermal contraction is relatively large isformed by the thermal deformation coping portion 10 and all metal plates6 forming the thermal deformation coping portion 10 are provided withthe slits 11 intersecting the longitudinal direction of the thermaldeformation coping portion 10, thereby absorbing the expansion orcontraction of the metal plate 6 due to the thermal expansion or thermalcontraction by the slits 11. Accordingly, since it is advantageous todecrease a compressive force generated by the thermal expansion or atensile force generated by the thermal contraction, it is possible toeffectively prevent the damage of the gasket 1 due to a change intemperature.

Further, since the slits 11 of the laminated metal plates 6 areseparated from each other in the longitudinal direction of the thermaldeformation coping portion 10 so that the slits 11 of the adjacent metalplates 6 do not overlap each other and the slits 11 do not penetrate inthe lamination direction, it is possible to prevent an unnecessarypenetration portion from being formed at the thermal deformation copingportion 10. Accordingly, it is advantageous to prevent a deteriorationin sealing performance in the lamination direction of the thermaldeformation coping portion 10 generated when the slit 11 is provided.

Accordingly, as in the embodiment, in the case of the gasket 1 havingthe partition protector 3, since the partition protector 3 is providedwith the thermal deformation coping portion 10, it is possible to keep ahigh thermal barrier effect of the partition protector 3 while absorbingthe expansion or contraction of the metal plate 6 due to the thermalexpansion or thermal contraction by the slit 11 formed at the thermaldeformation coping portion 10. That is, it is possible to effectivelyprevent the melting of the end surface of the partition portion 23 bythe partition protector 3 while effectively preventing damage due to achange in temperature of the gasket 1.

As in the embodiment, when the slits 11 of the metal plates 6 adjacentto each other in the lamination direction are disposed to be separatedfrom each other in the longitudinal direction of the thermal deformationcoping portion 10, the slits 11 which are adjacent to each other in thelamination direction do not easily overlap each other. Accordingly,since heat generated by a high-temperature fluid is not easilytransferred in the lamination direction through the slit 11, it isadvantageous to improve a thermal barrier effect of the thermaldeformation coping portion 10. When a distance between the slits 11adjacent to each other in the lamination direction is set so that theslits 11 adjacent to each other in the lamination direction do notoverlap each other at the time of using the gasket 1, it is moreadvantageous to improve the thermal barrier effect of the thermaldeformation coping portion 10.

When the slit 11 is formed to cross the thermal deformation copingportion 10, it is possible to more effectively absorb the expansion orcontraction of the metal plate 6 due to the thermal expansion or thermalcontraction in the thermal deformation coping portion 10 by the slit 11.For that reason, it is advantageous to prevent the damage due to thethermal expansion or thermal contraction of the gasket 1.

Further, when the slit 11 is formed at the center portion of the thermaldeformation coping portion 10 in the longitudinal direction, the metalplates 6 at both sides with the slit 11 as a boundary in the thermaldeformation coping portion 10 in the longitudinal direction can have thesubstantially same length. Accordingly, a change amount of the thermalexpansion or thermal contraction of the metal plates 6 at both sideswith the slit 11 as a boundary can be set to be substantially the same.Accordingly, even when the metal plate 6 is distorted due to the thermaldeformation, the deformation can be made uniform. Therefore, it isadvantageous to prevent the damage due to the thermal expansion orthermal contraction of the gasket 1. Further, in the embodiment, since aforce applied to a joint between the partition protector 3 and the mainbody portion 2 can be made substantially the same on the left and rightside, it is advantageous to prevent the deformation or damage of thepartition protector 3.

Further, when the slits 11 which are adjacent to each other in thelamination direction are respectively disposed at different sides withthe center position C of the thermal deformation coping portion 10 inthe longitudinal direction as a boundary, it is possible to secure asufficiently large gap between the slits 11 which are adjacent to eachother in the lamination direction while disposing the slits 11 at thecenter portion of the thermal deformation coping portion 10 in thelongitudinal direction. Accordingly, since an exhaust gas does noteasily pass through the slit 11 in the lamination direction, it isadvantageous to prevent the melting of the end surface of the partitionportion 23 by the partition protector 3.

As in the embodiment, when the thermal deformation coping portion 10 isprovided at the partition protector 3 suspended at the seal target hole7, the slit width W of the slit 11 formed at the thermal deformationcoping portion 10 may be set to a minimum size in which both slits 11 donot contact each other at the time of using the gasket 1. When the slitwidth W is set to a minimum size at which both slits 11 do not contacteach other at the time of using the gasket 1, heat of a high-pressurefluid is not easily transferred in the lamination direction through theslit 11. Accordingly, it is advantageous to improve the thermal barriereffect of the partition protector 3.

Additionally, in the embodiment, the gasket 1 which is used while beinginterposed between the pipe body 20 having one ventilation hole 22 andthe pipe body 21 having two ventilation holes 22 has been exemplified,but the present invention is not limited to the number, arrangement, orshape of the partition protector 3. In addition, various configurationcan be used. For example, in the case of the gasket 1 used while beinginterposed between the pipe body having one ventilation hole 22 and thepipe body having three ventilation holes 22, the partition protector 3may be provided at a plurality of positions.

The number of the laminated metal plates 6, the plate thickness ormaterial of each metal plate 6, the existence of the bead, or the likeis not particularly limited and can be appropriately determined inresponse to the joint structure to be used. In the embodiment, thethermal deformation coping portion 10 is provided so that the slit 11 isformed only at the partition protector 3, but, for example, a gapbetween the adjacent bolt holes 9 in the outer peripheral portion of themain body portion 2 may be formed as the thermal deformation copingportion 10.

FIGS. 5 and 6 illustrate a gasket 1 of a second embodiment according tothe present invention. The gasket 1 of the embodiment is used as a headgasket which is used while being interposed between the cylinder blockand the cylinder head of the internal-combustion engine.

The gasket 1 is formed by laminating three metal plates 6. Asillustrated in FIG. 5, the gasket 1 is provided with four bore holes 7 acorresponding to the seal target hole 7. Each bore hole 7 a is providedwith an annular seal portion 8 which seals an outer peripheral edge. Tenbolt holes 9 which fasten the cylinder block and the cylinder head toeach other are formed at the outer peripheral side of the seal portion8. A portion between the bore hole 7 a and the bolt hole 9 or a portionbetween the bolt hole 9 and the bolt hole 9 is provided with a pluralityof water holes 7 b and oil holes 7 c corresponding to the seal targethole 7. The seal portion 8 is provided at each of the outer peripheraledges of the water hole 7 b and the oil hole 7 c.

In the gasket 1, since cooling water for preventing an increase intemperature of an engine flows in the water hole 7 b, a portion close tothe water hole 7 b in the gasket 1 is cooled to a certain degree. Forthat reason, a portion close to the water hole 7 b of the gasket 1becomes a portion in which a change in expansion or contraction of themetal plate 6 due to the thermal expansion or thermal contraction isrelatively small. Further, since a distance between the bore holes 7 ais relatively short, a portion between the bore holes 7 a also becomes aportion in which a change in expansion or contraction of the metal plate6 due to the thermal expansion or thermal contraction is relativelysmall.

Meanwhile, since a portion between the bolt holes 9 which are adjacentto each other without interposing the water hole 7 b therebetween isrelatively distant from the water hole 7 b, a temperature thereof isrelatively higher than that of the other portion. Therefore, in thegasket 1, a portion in which a change in expansion or contraction of themetal plate 6 due to the thermal expansion or thermal contraction islarge becomes a portion (a shaded portion in FIGS. 5 and 6) interposedbetween the adjacent bolt holes 9 and this portion is formed as thethermal deformation coping portion 10. Additionally, a portion which isinterposed between the adjacent bolt holes 9 is, specifically, a portionsurrounded by the common external tangent of the two bolt holes 9 andthe outer edges of the bolt holes 9.

In the gasket 1, the slits 11 intersecting the longitudinal direction ofthe thermal deformation coping portion 10 are provided in all metalplates 6 constituting the thermal deformation coping portion 10interposed between the adjacent bolt holes 9. Then, these slits 11constitute the lamination portion of the metal plates 6 which do notpenetrate in the lamination direction. As illustrated in FIG. 6, theslits 11 of the metal plates 6 which are adjacent to each other in thelamination direction are disposed to be separated from each other in thelongitudinal direction of the thermal deformation coping portion 10. Thelongitudinal direction of the thermal deformation coping portion 10 ofthe embodiment indicates the axial direction in which the center of thebolt hole 9 is connected to the center of the bolt hole 9.

In the embodiment, the rectangular slit 11 is formed, but the shape ofthe slit 11 is not particularly limited. In addition, for example, theslit 11 may be formed in a rounded rectangular or elliptical shape. Aposition in which the slit 11 is formed may be set to a position inwhich a bead or shim is not provided in consideration of the surfacepressure or sealing performance of the gasket 1.

Each slit 11 is formed to cross the thermal deformation coping portion10. That is, the slit 11 is formed to intersect both of two commonexternal tangents of two bolt holes 9. Further, in the embodiment, eachslit 11 is formed to be orthogonal to the longitudinal direction of thethermal deformation coping portion 10. Further, each slit 11 is disposedat the center portion of the thermal deformation coping portion 10 inthe longitudinal direction.

As in the embodiment, in the gasket 1 used as the head gasket, anexpansion/contraction change amount of the metal plate due to thethermal expansion or thermal contraction increases in a portioninterposed between the adjacent bolt holes 9. For that reason, since aportion interposed between the adjacent bolt holes 9 is formed as thethermal deformation coping portion 10 provided with the slit 11, it ispossible to effectively decrease a compressive force generated by thethermal expansion or a tensile force generated by the thermalcontraction in the gasket 1. Accordingly, since the distortion of thegasket 1 is prevented, it is advantageous to keep the high sealingperformance.

A direction in which the metal plate 6 largely expands or contracts dueto a change in temperature becomes the longitudinal direction of thethermal deformation coping portion 10. Therefore, as in the embodiment,when the slit 11 is formed to be orthogonal to the longitudinaldirection of the thermal deformation coping portion 10, it is possibleto absorb the expansion or contraction of the metal plate 6 of thethermal deformation coping portion 10 in the longitudinal direction ofthe thermal deformation portion 10. Accordingly, since the metal plate 6is easily distorted, it is advantageous to prevent the damage due to thethermal expansion or thermal contraction of the gasket 1.

Additionally, in the embodiment, the gasket 1 which is used as the headgasket of the in-line four-cylinder engine has been exemplified, but thenumber, arrangement, or shape of the bore hole 7 a, the water hole 7 b,the oil hole 7 c, or the bolt hole 9 is not limited to the embodimentand can be set variously. Further, the number of the laminated metalplates 6, the plate thickness or material of each metal plate 6, or theexistence of the bead is not particularly limited and can beappropriately determined in response to the type of engine to be used.

FIGS. 7 and 8 illustrate a gasket 1 of a third embodiment according tothe present invention. The gasket 1 of the embodiment is used as amanifold gasket while being interposed between the cylinder head and theexhaust manifold of the internal-combustion engine.

The gasket 1 is formed by laminating four metal plates 6. As illustratedin FIG. 7, the gasket 1 includes a plurality of main body portions 4which seal the exhaust ports and a connection portion 5 which connectsthe adjacent main body portions 4.

Each main body portion 4 includes one seal target hole 7 and a sealportion 8 which seals the outer peripheral edge of the seal target hole7. Two bolt holes 9 for fastening the cylinder head and the exhaustmanifold to each other are formed at the outer peripheral side of theseal portion 8 of the main body portion 4. The gasket 1 includes fourmain body portion 4 and three belt-shaped connection portions 5 whichconnect the adjacent main body portions 4. The number or shape of eachof the main body portion 2 and the connection portion 5 or the number orarrangement of the bolt hole 9 is not limited to the embodiment and canbe set variously.

In the gasket 1 which is used as the manifold gasket, the connectionportion 5 which is interposed between the adjacent seal portions 8becomes a portion in which a change in expansion or contraction of themetal plate 6 due to the thermal expansion or thermal contraction isrelatively large and this portion is provided with the thermaldeformation coping portion 10 (a shaded portion in FIGS. 7 and 8). Inthe gasket 1, the rectangular slits 11 intersecting the longitudinaldirection of the thermal deformation coping portion 10 are provided inall metal plates 6 constituting the thermal deformation coping portion10 of the connection portion 5. Then, these slits 11 constitute thelamination portion of the metal plates 6 which do not penetrate in thelamination direction. As illustrated in FIG. 8, the slits 11 of themetal plates 6 which are adjacent in the lamination direction aredisposed to be separated from each other in the longitudinal directionof the thermal deformation coping portion 10. The longitudinal directionof the thermal deformation coping portion 10 of the embodiment is adirection in which the connection portion 5 extends to connect the mainbody portions 4.

In the gasket 1, each slit 11 is disposed at the center portion in thelongitudinal direction of the connection portion 5 corresponding to thethermal deformation coping portion 10 and each slit 11 is formed at theinside of the thermal deformation coping portion 10 so as not to cut theconnection portion 5.

As in the embodiment, in the case of the gasket 1 which is used as themanifold gasket, since the connection portion 5 is formed by the thermaldeformation coping portion 10 provided with the slit 11, it is possibleto absorb the expansion or contraction of the metal plate 6 due to thethermal expansion or thermal contraction in the connection portion 5 bythe slit 11. Accordingly, since it is advantageous to decrease acompressive force generated by the thermal expansion or a tensile forcegenerated by the thermal contraction, it is possible to effectivelyprevent the damage of the gasket 1 due to a change in temperature.

Further, since the slits 11 of the laminated metal plates 6 areseparated from each other in the longitudinal direction of the thermaldeformation coping portion 10 and these slits 11 are not formed topenetrate in the lamination direction, it is possible to prevent anunnecessary penetration portion from being formed in the connectionportion 5 corresponding to the thermal deformation coping portion 10.Accordingly, it is advantageous to keep the strength of the connectionportion 5.

Additionally, the configuration of the gasket 1 of the present inventionis not limited to the above-described embodiment as long as the gasketis formed by laminating two or more metal plates 6 and can be alsoapplied to the gaskets used for various purposes. Further, in thepresent invention, the thermal deformation coping portion 10 providedwith the slit 11 can be formed in all portions which are thermallydeformed due to the thermal expansion or thermal contraction in thegasket 1 and the thermal deformation coping portion 10 can be providedonly in a portion in which a thermal deformation due to the thermalexpansion or thermal contraction is particularly noticeable instead ofall portions.

For example, as in the second embodiment which is exemplified above, inthe case of the gasket 1 used as the head gasket, a portion located atthe intake side of the engine and a portion located at the exhaust sidethereof are provided, but in the gasket 1, a change in temperature inthe portion located at the exhaust side is larger than that of theportion located at the intake side. Therefore, it is possible to providethe thermal deformation coping portion 10 in which the slit 11 is formedonly at the portion located at the exhaust side.

REFERENCE SIGNS LIST

-   1 gasket-   2 outer peripheral portion-   3 partition protector-   4 main body portion-   5 connection portion-   6 metal plate-   7 seal target hole-   7 a bore hole-   7 b water hole-   7 c oil hole-   8 seal portion-   9 bolt hole-   10 thermal deformation coping portion-   11 slit-   20, 21 pipe body-   22 ventilation hole-   23 partition portion-   24 bolt hole

1. A gasket formed of two or more metal plates laminated together andcomprising at least one seal target hole penetrating in a laminationdirection, an annular seal portion sealing an outer peripheral edge ofthe seal target hole, and a plurality of bolt holes disposed at an outerperipheral side of the seal portion so that fastening bolts are insertedtherethrough, wherein all metal plates constituting the thermaldeformation coping portion includes slits, as a thermal deformationcoping portion, intersecting in a longitudinal direction of the metalplate and the slits constitute a lamination portion of the metal plateswithout penetrating in the lamination direction, and a portion suspendedin the seal target hole is formed at the thermal deformation copingportion when one seal target hole is provided, and at least one of aportion interposed between the adjacent seal portions and a portioninterposed between the adjacent bolt holes is formed at the thermaldeformation coping portion when the seal target hole is plural.
 2. Thegasket according to claim 1, wherein the slit is formed at a centerportion of the thermal deformation coping portion in the longitudinaldirection.
 3. The gasket according to claim 1, wherein the slit crossesthe thermal deformation coping portion.
 4. The gasket according to claim1, wherein two sides of the slits of the metal plates constituting thethermal deformation coping portion are set not to contact each other ata time of using the gasket.
 5. The gasket according to claim 1, whereinthe gasket is interposed between pipe bodies having different number ofventilation holes, the gasket includes a partition protector formed inone of the plurality of seal target holes; one of the plurality of sealportions; the plurality of bolt holes; and a partition protector whichis suspended in the seal target hole to cover a partition portion formedin the pipe body having a relatively large number of the ventilationholes, and the partition protector is formed at the thermal deformationcoping portion.
 6. The gasket according to claim 1, wherein the gasketis a head gasket used while being interposed between a cylinder blockand a cylinder head of an internal combustion engine, the gasketcomprises a plurality of bore holes which correspond to the seal targetholes; the seal portion which seals outer peripheral edges of the boreholes; and the plurality of bolt holes disposed at an outer peripheralside of the seal portion, and a portion interposed between the adjacentbolt holes is formed at the thermal deformation coping portion.
 7. Thegasket according to claim 1, wherein the gasket is a manifold gasketinterposed between an exhaust manifold and a cylinder head of aninternal combustion engine, and the gasket comprises a plurality of mainbody portions, each including one of the plurality of seal target holes,one of the plurality of seal portions, and the plurality of bolt holes;and a connection portion which connects the main body portions adjacentthereto, and the connection portion is formed by the thermal deformationcoping portion.